Burn-in of semiconductor devices is the acceleration of the life of the semiconductor devices using various combinations of voltage, temperature, and time. Burn-in predicts different quality levels of the semiconductor devices associated with time. Semiconductor manufacturers typically use burn-in to estimate the lifetime of semiconductor devices. In addition, burn-in is also a quality measure to estimate the number and/or the type of defects in the semiconductor devices over time. Burn-in is also used to accelerate a device past infant mortality. Infant mortality is an initial phase of device life. A device with a short life usually fails early in its life during the phase of infant mortality. Once a device has passed this initial phase of life, the device is more likely to function for many more years.
To burn-in a device, the device is usually loaded into a socket on a burn-in board (BIB). The BIB is the large circuit board used to hold and route signal traces for all of the devices undergoing burn-in. The BIB typically has a number of sockets to accommodate multiple devices. The devices are plugged into the sockets on the BIB, which is transferred into an oven for burn-in.
A driver for supplying the device stimulus and monitoring the device during burn-in is mounted at the back of the oven and coupled to the BIB after the BIB is loaded into the oven. An example of the driver is a Universal Burn-In Driver (UBID). Before burn-in, the oven temperature is ramped up to the desired level, which usually takes approximately 25 minutes. During burn-in, the device stimulus from the driver toggles as many gates in the device as possible. After burn-in, the oven is cooled down, which takes approximately another 25 minutes, before an operator can safely remove the BIB from the oven.
Currently, burn-in for chipset devices uses an expensive older generation Criteria 18 oven to control the junction temperature of the devices. The temperature range of Criteria 18 oven is limited. To burn in a chipset device at a temperature below the lower limit of the temperature range of Criteria 18 oven, an expensive heat sink is installed on the socket with each chipset device on the BIB to lower the temperature of the individual device to the desired burn-in temperature. Moreover, Criteria 18 oven has to operate at a high ambient temperature to be stable. Therefore, the interior temperature of the test floor has to be continuously monitored.
To control the oven and the driver, the current technology uses an external computer system. The computer system loads one or more burn-in patterns into the driver before burn-in. It usually takes 20-25 minutes to load the patterns. During burn-in, the driver uses the patterns to control the device to execute different tests.